Wet wiping printhead cleaning system using a non-contact technique for applying a printhead treatment fluid

ABSTRACT

A wet-wiping printhead cleaning system including a treatment fluid applicator placing treatment fluid on at least one of two elements involved in wiping, said two elements being a printhead orifice plate surface and a wiper, the system being so configured that treatment fluid is applied before wiping the printhead by projecting treatment fluid onto at least one element through the atmosphere, thereby avoiding direct contact between the applicator and said one element, the treatment fluid being placed so as to be available to assist in wiping a portion of the printhead orifice plate where the nozzle orifices are located to remove debris that may have accumulated, the treatment fluid lubricating the wiper so as to lengthen wiper service life and enhance wiping performance, as well as acting to render such accumulations more removable by wiping, the source of treatment fluid being uncontaminated by contact with either the printhead or the wiper.

RELATED APPLICATIONS

This application is related to three other co-owned applications filedconcurrently herewith, namely: U.S. patent application Ser. No.08/747,855, filed on Nov. 13, 1996 entitled WET-WIPING PRINTHEADCLEANING SYSTEM USING A TRANSFER ELEMENT, HP Docket No. 10961139; U.S.patent application Ser. No. 08/747,884, filed on Nov. 16, 1998 entitledWET-WIPING PRINTHEAD CLEANING SYSTEM USING A PRINTHEAD TREATMENT FLUIDSTORED IN A NON-FLOWABLE STATE, HP Docket No. 10961134; and U.S. patentapplication Ser. No. 08/747,857, filed on Nov. 13, 1996 entitledWET-WIPING PRINTHEAD CLEANING SYSTEM USING A DIRECT CONTACT TECHNIQUE,HP Docket No. 10961133.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the cleaning of printheads incomputer-driven printers of the type generally known as inkjet printers.More particularly, the invention relates to such cleaning in printersemploying a “wiper” which slidingly engages and wipes a nozzle orificeplate surface of a printhead to remove excess ink and accumulated debristo improve printhead performance and print quality.

2. Description of the Related Art

Ink-jet printing systems typically operate by ejecting ink from aplurality of small, closely-spaced nozzles located on the printhead. Forproper functioning, an ink-jet printhead must be routinely serviced.

During printing, stray droplets of ink, dust, paper fibers and otherdebris can accumulate around the nozzles on the orifice plate surfaceand interfere with the trajectory of subsequently ejected ink droplets,thereby affecting print quality. To minimize this, the ink-jet printheadcan be cleaned by intermittently wiping the orifice plate surface toremove the accumulated ink and debris.

During periods of inactivity, ink in the nozzles can dry or harden,plugging the nozzles. Thus, ink-jet printheads may be capped to maintainan appropriate environment around the nozzles and to postpone theirclogging. This capping may be done automatically after a short period ofinactivity, even during the middle of printing a page, if the printer iswaiting for more data.

Inkjet printers generally have a printhead service station to which aninkjet printhead is moved by carriage, and a cap which sealinglycontacts the printhead is generally located at the service station. Atthe service station, the printhead (or multiple heads if such are used)are occasionally cleaned and, if necessary, primed with ink. For use inthis cleaning function wipers are located at the service station. Theservice station can include a “sled” carrying these elements and othersrequired to service the one or more printheads of the printer. This sleditself can be moved transversely to an axis of motion of the printheadcarriage, for example in a vertical direction, so as to bring the capsor wipers for example into or out of contact with the printhead.Alternatively, a tumbler can be provided at the service station, andwipers, as well as caps, can be located on the tumbler. Rotation (and insome cases also vertical movement) of the tumbler effects wiping of theprinthead, and/or alignment of one or more caps with one or moreprintheads positioned adjacent the tumbler at the service station.

To improve printing speed and the clarity and contrast of the printedimage, recent advancements in the art have focused on improving the inkitself. For example, to provide faster, more waterfast printing withdarker blacks and more vivid colors, improved pigment-based inks forinkjet applications have been developed. These pigment-based inks have ahigher suspended solids content than earlier dye-based inks. Both typesof ink dry quickly, which allows inkjet printing mechanisms to use plainpaper. However, the combination of small nozzles and quick-drying inkleaves the printheads susceptible to clogging, in this case not onlyfrom the dried ink and minute dust particles or paper fibers, but alsofrom the solids within the inks themselves. Further, this dried ink ismore difficult to remove the previously used dry-based inks when dried.These characteristics compound the problems affecting print qualitymentioned above.

Another characteristic of these pigment-based inks contributes to thenozzle clogging problem. The pigment-based inks use a dispersant to keepthe pigment particles from flocculating. Unfortunately, the dispersanttens to form a tough film on the printhead orifice plate face as the ink“vehicle” or carrier component of the pigment-based ink evaporates.Besides the debris accumulated on the printhead face from inkover-spray, paper crashes and printer printing for example, thisdispersant film also attracts and binds paper dust and othercontaminants as well as solid from the ink itself. It has beenrecognized that this film, as well as ink residue and debris surroundingthe printhead nozzles, is quite difficult to removed from the printhead.

Known cleaning systems used in printers of this type employ wipers whichincorporate a blade formed of an elastomeric material such as a vinyl orEDPM. The wiper blade and a printhead are moved relative to one anotherso that the blade wipes accumulation from the critical area of theprinthead incorporating the nozzle orifices. This system is not alwaysfully effective even with older, dye-based inks. Some systems employ asecond wiper formed of a soft absorbent material to further clean or“buff” the printhead. In other printhead servicing systems ink from thepen is ejected or drawn out and used to help lubricate the wiper anddissolve ink residues adhering to the printhead, with the goal ofimproving cleaning effectiveness. While this later scheme works wellwith some dye-based ink systems, it involves wasting ink that wouldotherwise be used for printing. Such a system is disclosed incommonly-owned U.S. Pat. No. 5,103,244 issued Apr. 7, 1992 to Gast, etal. and U.S. patent application Ser. No. 398,709 filed Mar. 6, 1995, thedisclosures of which are incorporated herein by reference.

Furthermore, cleaning systems using ink drawn from the printhead do notwork as well, generally speaking, with high-solids waterfast inkformulations. Reasons for this include the dried residue from such inksbeing more resistant to breakup and removably mechanical forces appliedby the wiper as mentioned above, and that the kinetics of redissolutionare slow in these inks. These factors, for example, limit theeffectiveness of this known cleaning process, and that is undesirable.Also, with this system more ink residue collects on the wiper, and someof these accumulations can be pushed back into the nozzles of theprinthead which can at least temporarily cause one or more nozzles notto fire properly, degrading print quality.

It has been recognized that application of a fluid solvent or othertreatment fluid to the printhead will mitigate the problem of dried inkby showing the drying of ink or redissolving ink residues, rendering theprinthead easily cleanable by wiping. However, many problems associatedwith use of a treatment fluid have been identified.

Storage of the treatment fluid in adequate amounts for the life of theprinter without leaking is problematic. For example leaks can occur dueto tipping the printer and pressure differentials due to a charge intemperature or altitude during shipment. Another problem recognized isapplication of treatment fluid to a printhead having undesirableaccumulation of ink solids, dispersants, and other debris withoutcontamination of the source of treatment fluid by such accumulations. Itis desirable to maintain the means of applying treatment fluid and thetreatment fluid itself in an uncontaminated state to provide consistingprinthead cleaning over the life of the printer. Also, metering theamount of treatment fluid applied in wiping is recognized as important.Consistent optimally cleaning effectiveness as well as print quality canbe compromised by application of too little or too much treatment fluid.Too little treatment fluid results in less effective residue removalallowing undesirable accumulation. Too much treatment fluid can resultin one or more nozzles being at least temporarily disabled due to excesstreatment fluid being pushed into the nozzle by the wiper, or drawn intothe nozzle by negative pressure associated with operation.

In sum there are many problems, including identifying optimal ways ofapplying treatment fluid to enhance wiping effectiveness, that have beenidentified but not resolved in known cleaning systems. It is thereforerecognized that an improved cleaning system, particularly for printersusing pigment-based inks employing high solids content and dispersants,is needed to provide and maintain optimal functioning of thermal inkjetprintheads.

SUMMARY OF THE INVENTION

The present invention accordingly provides a system for servicing aportion of a printhead of an inkjet printer of the type having aprinthead reciprocally moved by a carriage and a wiper positioned andadapted to move relative to the printhead in wiping contact therewith toremove unwanted accumulations from a portion of the printhead to becleaned when the printhead and the wiper are moved relative to eachother by movement of at least one of the two elements consisting of theprinthead and the wiper. The system includes a source of printheadwiping treatment fluid. It also includes projecting treatment fluidthrough the atmosphere in a reproducible quantity from the source oftreatment fluid onto at least one of the said two elements (printheadand wiper) so as to be available to assist in wiping. The systemprovides for wiping the printhead by relatively moving the wiper and theprinthead subsequent to placing the treatment fluid on at least one ofthese elements.

In a further more detailed aspect, the invention further includesproviding an applicator adapted to place treatment fluid in areproducible quantity on the surface of at least one of the printheadand wiper elements by projecting the treatment fluid through theatmosphere onto at least one of the printhead and wiper elements,avoiding direct contact therewith. Additional steps include transportingtreatment fluid from the source of printhead treatment fluid to theapplicator and projecting treatment fluid onto at least one element. Thesource of printhead treatment fluid can be permanently located orreplaceable.

In more detail the invention further includes the option of providing asource of treatment fluid that acts both as a treatment fluid reservoirand as an applicator. The source of treatment fluid can incorporate atreatment fluid-jetting apparatus employing on demand drop ejectiontechnology, and projecting jettable treatment fluid therefrom towards atleast one element of the two elements consisting of the printhead andthe wiper. Such a fluid jetting apparatus can be a cartridge havingtherein a treatment fluid reservoir and an on demand drop ejection meansfor projecting treatment fluid, and such a cartridge can be replaceable.Accordingly, in another more specific aspect the source of treatmentfluid can be either permanently located within the printer or it can bea replaceable component.

In another detailed aspect the apparatus for projecting treatment fluidcan comprise a low-volume spray pump. Such a spray pump can be connectedby a conduit to a treatment fluid reservoir. The pump can be actuated byan actuator controlled by the printer controller or actuated by movementof structure carrying the element to which treatment fluid is applied,being the carriage, a service station tumbler or sled, or by movement ofother structure coordinated with movement of the printhead or wiper.

In a further more detailed aspect, the apparatus for projectingtreatment fluid through the atmosphere can include a spring which iselastically deformed and is adapted to impart energy to the treatmentfluid or structure coupled to treatment fluid so as to impel treatmentfluid toward at least one of the printhead and wiper elements on reboundof the spring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective partly cutaway view of a computer drivenprinter, illustrating the environment of the invention in oneembodiment.

FIG. 2 is a front elevation partly in section of a portion of a servicestation of the printer of FIG. 1 showing four carriage-borne pencartridges in proximity to the service station taken along line 2—2 inFIG. 1.

FIG. 3 is an elevational view, partly in cross section, taken along line3—3 in FIG. 2.

FIG. 4 is an elevational view, partly in cross section taken along line4—4 in FIG. 2.

FIG. 5 is an exploded perspective view of the portion of the servicestation sled, including a treatment fluid reservoir and wick applicatorwick container, cap, wiper and wiper mount seen in FIG. 2.

FIG. 6 is a schematic perspective illustrating an alternate embodimentof the invention shown in FIG. 5, having a further treatment fluidreservoir and conduit for periodically replenishing treatment fluid atthe wick applicator.

FIG. 7 is a elevation view, partially in break-away section, of a penaccording to an alternate embodiment of the invention.

FIG. 7A is a sectional elevation view of a portion of the pen shown inFIG. 7 illustrating further alternate embodiment of the invention.

FIG. 8 is a elevation view, partially in section, of a service stationarea of an alternate embodiment of the invention.

FIG. 9 is an elevational view, partially in section, of an alternateembodiment of the invention.

FIG. 10 is an illustration of the modes of operation of the embodimentof FIG. 9.

FIG. 11 is a schematic illustration, partially in break-away section, ofan alternate embodiment of the invention.

FIG. 12 is a elevational view, partially in section, of a portion of aservice station illustrating an alternate embodiment of the invention.

FIG. 13 is a elevational view, partially in section, of a portion of aservice station illustrating an alternate embodiment of the invention.

FIG. 14 is a elevational view, partially in section, of a portion of aservice station illustrating an alternate embodiment of the invention.

FIG. 15 is a perspective view, partially in cut-away, of a furtherprinter, illustrating the environment of an alternate embodiment of theinvention.

FIG. 16 is a perspective view, in partial cut-away, of a service stationaccording to an alternate embodiment of the invention shown in FIG. 15.

FIG. 17 is an elevational representation, partially in section, of theembodiment of the invention shown in FIG. 16 taken along line 17—17 inFIG. 16.

FIG. 18 is a schematic representation, partially in section, of analternate embodiment of the invention shown in FIG. 17.

FIG. 19 is a sectional elevational view of a source of treatment fluidin a alternate embodiment of the invention.

FIG. 19A is a sectional view of a source of treatment fluid in aalternate embodiment of the invention to that shown in FIG. 19.

FIG. 20 is a sectional elevation view of a source of treatment fluid ina alternate embodiment of the invention.

FIG. 21 is a perspective schematic representation, in partial-away, ofan alternate embodiment of the invention.

FIG. 22 is a perspective schematic representation, in partial cut-away,of an alternate embodiment of the invention.

FIG. 23 is a sectional elevation view of a source of treatment fluidaccording to an alternate embodiment of the invention.

FIG 24 is a sectional view of source of treatment fluid in anotheralternate embodiment incorporated in a service station of the printer ofFIG. 1.

FIG. 25 is a sectional view of source of treatment fluid in anotheralternative embodiment incorporated in the printer of FIG. 15.

FIG. 26 is a schematic illustration, partially in section, of analternate embodiment of the invention.

FIG. 27 is a schematic representation, partially in section, of analternate embodiment of the invention.

FIG. 28 is a schematic representation, partially in section, of analternate embodiment of the invention.

FIG. 29 is a schematic representation, partially in section, of analternate embodiment of the invention incorporated in the printer ofFIG. 1.

FIG. 30 is a schematic representation, partially in section, of analternate embodiment of the invention incorporated in the printer ofFIG. 15.

FIG. 31 is a schematic representation, partially in section, of analternate embodiment of the invention incorporated i the printer of FIG.1.

FIG. 32 is a schematic representation, partially in section, of analternate embodiment of the invention incorporated in the printer ofFIG. 15.

FIG. 33 is a schematic perspective illustration of the alternateembodiment of the invention.

FIG. 34 is a schematic perspective illustration of the alternateembodiment of the invention.

FIG. 35 is a schematic perspective illustration of the alternateembodiment of the invention.

FIG. 36 is a schematic illustration of another embodiment of theinvention.

FIG. 37 is a schematic illustration of another embodiment of theinvention.

FIG. 38 is an elevational schematic representation partially in section,of an alternate embodiment of the invention representation taken fromdirection line 38—38 in FIG. 39.

FIG. 39 is an elevational schematic illustration partially in section,of the alternate embodiment of FIG. 38 taken from direction line 39—39in FIG. 38.

FIG. 40 is a perspective representation, partially in section, of aalternate embodiment of the invention.

Certain reference numbers are used to refer to certain like elements inthe various embodiments shown in the figures. However, this is purelyfor convenience. Use of the same or different reference numbers for anyelement is not to be construed as limiting the invention, or to implyelements are in all ways the same or different.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1 of the drawings, which are provided by way ofexemplary illustration, and not by way of limitation, there is shown anembodiment of an inkjet printing mechanism, here shown as an inkjetprinter 10, constructed in accordance with the present invention. Suchprinters may be used for printing for business reports, correspondence,desktop publishing, and the like, in an industrial, office, home orother environment. A variety of inkjet printing mechanisms arecommercially available. For instance, some of these printing mechanismsthat may embody the present invention include plotters, portableprinting units, copiers, cameras, and facsimile machines, to name a few,but for convenience the concepts of the present invention areillustrated in the environment of an inkjet printer 10.

While it is apparent that the printer components may vary from model tomodel, the typical inkjet printer 10 includes a chassis 12 and a printmedium handling system 14 for supplying a print medium 13 to the printer10. The print medium can be one of numerous types of suitable sheetmaterial, such as paper, card-stock, transparencies, mylar, foils, etc.depending on the application, but for convenience, the illustratedembodiment is described using paper as the print medium. The printmedium handling system 14 moves the print media into a print zone 15from a feed tray 16 to an output tray 18, for instance using a series ofconventional motor-driven rollers (not shown). In the print zone 15, themedia sheets receive ink from an inkjet pen cartridge, such as a blackink pen cartridge 20 and/or one or more color ink pen cartridges 22, 24,26. The illustrated embodiment employs a group of 4 discrete monochromepens, however in other embodiments, for example, a tri-color pen can beused with a monochrome black ink pen, or a single monochrome black pen20 may be used alone.

The illustrated pen cartridges 20, 22, 24, 26 each include reservoirsfor storing a supply of ink therein, although other ink supply storagearrangements, such as those having reservoirs mounted on the chassis 12and fluidly connected by a flexible conduit for example, may also beused. The cartridges 20, 22, 24, 26 incorporate printheads 30, 32, 34,36 respectively. With reference also to FIGS. 2, 3 and 4, as is known inthe art each printhead has an orifice plate surface 40 with a pluralityof nozzles (not shown), formed therein in a manner well known to thoseskilled in the art. The illustrated printheads 30, 32, 34, 36 arethermal inkjet printheads, although it will be understood that othersimilar printheads are to be included in the scope of application of theinvention. The printheads 30, 32, 24, 26 typically include a pluralityof resistors (not shown) which are associated with the nozzles. As isknown, upon energizing a selected resistor a drop of ink is ejected fromthe nozzle and onto a sheet of paper 13 in the printer zone 15 under thenozzle.

Returning to FIG. 1 particularly, the pen cartridge 20, 22, 24, 26 aretransported by a carriage 42 which may be driven along a guide rod 44 bya conventional drive belt/pulley and motor arrangement (not shown). Thepens selectively deposit one or more ink droplets on a sheet of paper 13in accordance with signals received via a conductor strip (not shown)from a printer controller, such as a microprocessor (not shown) locatedwithin the chassis 12. The controller typically receives instructionsfrom a computer, such as a personal computer (not shown). The printheadcarriage 42 and paper handling system 14 also operate in response tocontrol signals form the printer controller in a manner well known tothose skilled in the art. The printer controller may also operate inresponse to user inputs provided through a key pad 46.

The printer chassis 12 defines a chamber 48 that provides a printheadservicing region including a service station 50, supported by thechassis and located at one end limit of the travel path of the carriage42. The service station 50 includes a vertically moveable platform orframe referred to herein as a sled 52, supported by the service stationwithin the servicing region. The sled is configured to support variousservice station components, such as wipers, caps, and priming units. Avariety of suitable capping and printing designs are known andcommercially available. In one embodiment (not shown) one or more wipersmay be positioned stationary and only the caps are vertically moveable.

Referring now to FIG. 2, the illustrated service station 50 includes thesled 52, which itself embodies printing units 54, 56, 58, 60 formedunitary therewith. A filter 62 is inclosed in each priming unit toprevent ink from being drawn into a priming vacuum line 64. The primingunits draw ink from the printheads 30, 32, 34, 36 in clearing thenozzles (not shown) terminating at the orifice plate surface 40 of eachprinthead. This is done when the pen being primed is aligned with apriming unit, also with a cap 66. The cap is brought into sealingcontact with the printhead 30, 32, 34, or 36, and a vacuum is applied.Ink drawer from the nozzles may collect on the orifice plate surface 40of each pen primed. Further, as mentioned, debris such as paper fibersor dried ink for example may collect on the orifice plate surface.Capping the pens minimizes the drying of ink, but if dried ink (mixed ornot with other debris) is present before a pen is capped, and/or the penis capped for a long period of time before the pen is primed, driedaccumulations may be present as well as freshly drawn ink occasioned bythe priming process. The sled has a first, capped, position, a secondwipe position and a third clear position, the position of the sled beingcoordinated with movement and position of the printhead carried by thecarriage 42 to allow the printhead to pass or be aligned with componentsof the service station as desired, and to come into contact or not witha wiper 70 for example.

Before a primed pen 20, 22, 24, or 26 is again moved to the print zone15 to print, these accumulations are removed in this embodiment bymoving the sled to the wiper position and passing the printhead 30, 32,34, or 36 desired to be cleaned past the wiper 70 which is carried by aspring mount 72. As seen in FIG. 3, the wiper 70 is positioned so as tointerfere with the travel of the printhead 34, even after the sled 52 ismoved downward and away from the printhead to the wipe position so as toun-cap the pen and allow such travel. The spring mount 72 deflects asrequired as the wiper is pushed downward by the printhead to let theprinthead pass. A resulting rebound force is applied to the wiper,holding it against the orifice plate surface 40 for example as theprinthead passes. As will be apparent, the wiping action of the relativemovement between the printhead and wiper is intended to wipe or scrapeink and other accumulations from the orifice plate surface, with thedesired result being improved printhead function and print quality.

As mentioned however, often in known devices the wiping action is lesseffective than desired. This can be due for example to the wiper beingworn from numerous previous wiping cycles and/or dried accumulationsbeing too firmly attached to the orifice plate surface to be removed inthis way.

Referring now to FIGS. 2 and 4, in the illustrated embodiment of theinvention the effectiveness of the wiping action is improved,particularly with regard to relatively more quickly drying pigment-basedinks, by providing treatment fluid from a source 73 of treatment fluid74 including a fluid container 76 sealingly attached to the underside ofthe sled 52 forming a closed fluid reservoir chamber 78 near a cap 66 ofthe service station 50. For purposes of illustration, the discussionherein will be directed to application of the invention to a single pen20 of the multiple pens 20, 22, 24, 26 carried by the carriage (42 ofFIG. 1) and the associated service station structure 50 penetrating tothis pen. In the exemplary embodiment the pen 20 is a black ink penwhich utilizes an ink having a relatively high pigment content andfast-drying characteristics. However, it will be understood by oneskilled in the art that the discussion is applicable to each and all ofthe pens used in the printer 10.

The treatment fluid 74 serves one or more of several functions dependingupon the particular application. First, it lubricates the wiper 70 inwiping so as to reduce wear of the wiper. As is readily appreciated,wiper function is dependent on maintaining a desired wiper geometry, forexample a wiper edge 84. Wear changes this geometry, for example bydegradation of this edge over the life of the printer 10 to a rounded oruneven shape. Lubrication of the wiper accordingly provides betterwiping function over the life of the printer by reducing wear of thewiper.

A second benefit of the treatment fluid 74 is that it dissolves some ofthe dried ink residues accumulated on the printhead 30. This allows suchdeposits to be more easily removed.

Third, the treatment fluid 74 helps the wiper 70 to transport bothdissolved ink and other dried residue and accumulations in wiping. Thisresults in a more thorough removal of such debris.

A fourth function of the treatment fluid 74 is that a thin film offluid, which does not dry, is left on the printhead 30. Ink residue andother debris subsequently deposited on the printhead over this layer offluid are more easily wiped off as they have less tendency to adhere tothe printhead.

The treatment fluid used in the exemplary embodiment, polyethyleneglycol (PEG), is relatively non-volatile, and relatively viscous. Again,depending on application, other fluids may be used, for example havingproperties selected for optimal performance with the particular inkbeing used. Treatment fluids that have been found to work well withpigment-based inks are generally characterizable in that they arewater-soluble, somewhat viscous, and relatively non-volatile. Dependingon the application PEG having an molecular weight of between about 200and 600 is used. It has been found that by mixing PEGs of differingmolecular weights treatment fluid properties can be varied to performoptimally in various embodiments of the invention for example.

Variation of the material comprising the treatment fluid 74, and theproperties of a given material can be made so as to emphasize anyfunction, such as lubrication, to increase wiper and printhead 30 life.Or alternatively, for example, it could be selected to best helpdissolve ink residue and/or prevent residue and contaminants fromadhering to the printhead.

An applicator, being in the illustrated embodiment a wick 80, isprovided which draws treatment fluid from the fluid chamber 76 bycapillary action, and is disposed through an opening 82 in the sled 52between the cap 66 and wiper 70. Thus positioned it extends upwardbeyond the sled sufficient distance to contact the printhead 30 when itis in the capped position. A small reproducible amount of treatmentfluid is deposited on the orifice plate 40 of the printhead 30 as aresult of this contact. This treatment fluid is placed adjacent an edgeof the plate nearest the wiper at a location wiped by the wiper so as tobe available to the wiper in a subsequent printhead wiping operation.The wiper 70 will first come in contact with the deposited treatmentfluid and thereafter wipe across the portion of the orifice plate to becleaned. This can be made to occur each time the printhead 30 is wipedfor example. As will be apparent, if the pen is not otherwise to becapped, the operation of dabbing, or depositing treatment fluid on theprinthead orifice plate before wiping in this way is performed in arelatively short time. Also application of treatment fluid to printheadcan be combined with priming.

In another embodiment (not shown), the applicator wick can be carried bya spring-mounted gimbal. Freedom of movement about two perpendicularaxes for example provides uniform contact between such an applicatorwick and a printhead.

The amount of fluid deposited depends on the surface area of thecontact, the pore size of the applicator wick used, the properties ofthe surface of the orifice plate 40, the properties of the treatmentfluid, and the relative force (if any) applied at the contact point dueto relative positioning for example, or that applied as a result of aspring mounting (not shown) being used. In the illustrated embodimentthe fluid supply is intended to be sufficient for the life of theprinter, accordingly only a small amount of fluid is transferred to theprinthead each time the wick makes contact.

In the illustrated embodiment the wick 80 is positioned to just come incontact with the printhead 30 when the pen 20 is capped. Force greatenough to appreciably deform the wick is not applied to the wick by theprinthead and vice-versa. The size of a rectangular area at the tip ofthe wick which comes in contact with the surface 40 of the printhead isapproximately 12 millimeters by 0.5 millimeters. The relative porosityof the wick is characterized by a pore size of approximately 60 microns.The treatment fluid used is a PEG of molecular weight 400. Thiscombination has been found to work well with presently-known andcommercially-available orifice plates, for example those sold throughoutthe world by the assignee of the present invention.

In a further alternate embodiment, the applicator wick 80 is positionedso as to not contact the printhead 30 while capped, but rather, wipinglycontact the printhead as the printhead it moves past along its path ofmotion with the carriage and deposits treatment fluid on the printhead.This wiping contact occurs when the sled is in the second, or wipingposition. As the printhead 30 moves towards the print zone, the wickapplies treatment fluid as said printhead moves past the applicatorwick. Subsequently, the wiper wipes the orifice plate, clearingtreatment fluid and unwanted accumulations therefrom.

In the illustrated embodiment, the applicator wick 80 is stabilized bythe shape of the container 76 and by a second wicking material block 86which fits snugly within the fluid container 76. This is perhaps bestappreciated as shown in FIG. 5. An open-cell foam for example may beused to form the second wicking block. The foam should be selected so asto be compatible with the treatment fluid. Polyurethane foam can be usedwith PEG treatment fluid for example. The fluid is transported bycapillary action through this block to the applicator wick 80, which canbe formed of a material having relatively higher capillary attractionforce properties. The applicator wick itself can be formed so as to havegreater capillary attraction forces acting in and adjacent its upperextract which actually contacts the printhead 30 for example bycompressing the applicator wick in this location. The applicator wick inany case is continuously supplied with treatment fluid which is drawnupward for application to the printhead.

With reference to FIGS. 2, 4 and 5, in more particularity aftertreatment fluid 74 is deposited on the orifice plate 40, with subsequentrelative movement of the wiper 70 across the printhead 30 the wipermoves the treatment fluid in front of it. This fluid wets the wiper andthe surface of the printhead, particularly the orifice plate outersurface 40 in the area of the nozzles, and the wiper provides any one ormore of the beneficial actions discussed above that the selected fluidused is desired to provide. As is often the case in printhead cleaningsystem designs, a scraper (not shown) is provided to removeaccumulations from the wipers so that it is clean for the next time thewiper wipes the printhead.

The closed chamber 78 containing the supply of treatment fluid 74 isscaled but for the opening 82 through the sled 52. The configuration ofthe container, sled, applicator wick, and second reservoir wicking block77 formed of a porous media such as rigid or elastomeric open-cell foamwhich completely fills the chamber, acts by capillary forces to preventtreatment fluid from leaking from the chamber during shipment forexample. As can be appreciated, a small vent opening 79 can be providedto allow air to enter as fluid is withdrawn.

Other embodiments of the invention employ any of several types oftreatment fluid sources, as discussed below including chambers disposedelsewhere in, on, or adjacent the service station 50, or, alternatively,collapsible flexible enclosures such as accordion folded envelopes orsimple bags formed of a flexible material. In any case the treatmentfluid source should be designed to prevent leaking of the fluid. Inrigid chamber constructions, having an opening for admitting air, thiscan be accomplished by filling the chamber with a porous media such asfoam, as shown, or fibers (oriented or random) to provide pore spacessmall enough so that capillary action will prevent fluid from leaking,or providing a one way valve at the air intake opening. With a flexiblebag containing only treatment fluid, leaking due to air expanding in thechamber due to a temperature change during shipping, for example, can beprevented as a vent is not required due to collapsibility of the bag. Inthis latter embodiment the flexible bag is connected by conventionalmeans to a tube, in turn conventionally connected to a housing of a wickholder comprising the wick applicator, the holder being mounted (forexample by a spring gimbal mount) at the proper location adjacent awiper.

In further alternate embodiments (not shown) the treatment fluid is fedby gravity from a reservoir to a wicker holder. The wick holder canenclose all but the tip of the applicator wick, which tip can have ahigher capillary force than the rest of the applicator wick (formed forexample of another material). Treatment fluid is drawn to the tip bycapillary action and subsequently applied to the printhead.

In another embodiment, shown schematically in FIG. 6, in order to keeptreatment fluid from leaking during shipment or other movement, such asturning the printer on a side to connect cables for example, a normallyclosed solenoid valve 88 is provided in a tubing line 90 connecting awick holder (such as the container 76 and sled 52 of the illustratedembodiment) with a further treatment fluid reservoir 92. This solenoidvalve can be controlled by the printer controller 94 so as to be openonly when a specific printer operation is taking place for examplemoving the carriage or uncapping a printhead in normal operation, theprinter operation being selected to be incompatible with movement ortipping of the printer 10 which could cause filled 74 to leak from thesystem, such as in shipping, for example. In this way it can bevirtually assured that there will be no leaks.

Alternatively, the flow of treatment fluid to the applicator wick 80through the line 90 can be controlled by other means (not shown) so thatfluid will never leak. One means for example is to use a switch ormechanical valve that is open only when the printer is upright and inoperation.

As can be appreciated, the embodiment of FIG. 6 could be employed inconnection with controlling flow of treatment fluid to the applicatorwick for another reason. For example, a relatively more volatiletreatment fluid could be dosed to the applicator wick only as neededjust prior to application to the printhead.

Referring to FIG. 7, in a further alternate embodiment the treatmentfluid is contained in a reservoir 100 filled by a porous material 108disposed within the pen cartridge 20 itself, and dispensed by anapplicator wick 102 configured so that a surface portion 104 of the wickforms a portion of a wiped outer surface 106 of the printhead portion 30of the pen cartridge 20. Treatment fluid is thereby transported to andplaced at the outer surface of the printhead by and through the wickapplicator. The location of the surface portion 104 of the outer surfaceof the printhead comprising the wick is adjacent a leading edge or sideof the printhead which is first contacted by the wiper 70 in wiping theprinthead. Accordingly treatment fluid made available there between theorifice plate 40 and the leading edge or side where it will be contactedby the wiper before the wiper continues across the outer surface 106 ofthe printhead. The wiper is wetted in connection with wipingly engagingthe wick applicator portion of the outer surface of the printhead. Then,pushing treatment fluid before it, the wiper moves across the portion ofthe printhead to be cleaned, for example the critical area adjacent thenozzle orifices in wiping contact therewith.

Among the possible ways to implement this embodiment of the presentinvention a design found to work well involves incorporating a porousopen cell rigid foam block 108 in the treatment fluid reservoir 100incorporated in the pen 20. This foam block completely fills thereservoir and is impregnated with treatment fluid. In a furtherembodiment (not shown) the wick 102 is eliminated and an exposed portionof this foam is positioned to intercept the wiper 70 in relative wipingmovement.

Referring to FIG. 7a in another alternate embodiment the wick applicator102 is replaced by a “capillary” applicator 109 comprising two identicalelastomeric flap components 110, 111 having planar opposed surfacesseparated by a capillary space 112 therebetween. It has been found thattreatment fluid migrates in the capillary space between the two halvesof the applicator and is available at a tip portion 114 to betransferred to the wiper by wiping contact between the wiper and thecapillary applicator.

An example of a device where a treatment fluid is carried with the pen,and a device having a two-piece wiper having two pieces with opposedsurfaces and a capillary space therebetween for conveying a treatmentfluid to the tip of the wiper is disclosed in commonly-owned U.S. Pat.No. 5,300,958 issued Apr. 5, 1994 to Burke, et al., the disclosure ofwhich is incorporated herein by reference.

As will be apparent, this pen-mounted treatment fluid source allowsreplacement of the treatment fluid supply with each new pen cartridge20. This embodiment allows a smaller amount of treatment fluid to bestored and reliably dispensed (one pen life vs. a printer lifetimesupply), and allows the lubricant to be more closely matched with theproperties of the ink used. This later consideration is particularlynoteworthy as it allows improvement of the ink formulations used overthe lifetime of the printer without needing to consider the propertiesof the treatment fluid embodied in existing printers.

Returning now to FIG. 5, it can be appreciated that assembly of the fewsimple components of the embodiment is easily accomplished by placingthe applicator wick 80 and second wicking material block 86 into thetreatment fluid container 76 and filling the container with treatmentfluid 74. The block 86 fits tightly in the container and holds theapplicator wick in a channel 97 adapted to receive the applicator wick,the components cooperating to hold the applicator wick in correctalignment for assembly.

The treatment fluid container 76 is then joined to the sled by solventor sonic welding, or by use of an adhesive for example, passing theapplicator wick through the opening 82 to do so. The treatment fluidcontainer 76 is configured to provide a receptacle 98 which receives theprinting unit 60 of the sled 52. In another operation a wiper 70 formedof an elastomeric material having desired properties is mounted on aspring mount 72 which is retained against the sled by a portion of aretainer 96 which cooperates with the sled for this purpose.

With reference now to FIG. 8, in another embodiment treatment fluid 74is contained in a separate applicator housing 116 carried by the guiderod 44 and biased to a first position 117 between the service station 50and the print zone 15 of the printer by a coil spring 118. Theapplicator has a chamber 120 filled by a wicking material such as anopen-cell foam. The foam is in contact with a wicking nib applicator 122which protrudes below the housing and is configured to apply treatmentfluid in small reproducible quantities to elastomeric wipers 124positioned on the service station sled 52. The applicator housingfurther comprises scraper portions 126 configured to contact the wipersin scraping fashion to remove unwanted accumulations that may be presenton the wipers.

In operation the carriage 42 moving towards the service station 50 firstcontacts the applicator housing 116 at the first position 117 and movesthe applicator ahead of the carriage across the service station to asecond position 119 where it remains while the pens 20, 22, 24, 26 arepositioned adjacent their respective caps 66 for servicing or when capedbetween printing operations for example. As the carriage moves towardthe print zone 15 from the service station 50 the applicator housing 116follows the carriage 42 due to the rebound force of the biasing coilspring 118. As the applicator housing 116 traverses the service stationin each direction the wicking tip applicator wipingly contacts thewipers 124 and deposits a small reproducible amount of treatment fluid,for example such as 1-5 microliters of PEG, to each wiper to assist inwiping as before described. As can be appreciated in this embodimenttreatment fluid is first applied to the wiper 124, rather than theprinthead 30. It will be noticed also that wiping in both directions ofcarriage travel occurs in this embodiment, and that treatment fluid issimilarly applied to the wipers.

This embodiment gives the advantage of dosing the wipers 124 withtreatment fluid by an applicator 122 moving with the pens 20, 22, 24, 26without having to mount it (or a reservoir 120 of treatment fluid tosupply it) on the carriage 42. In another embodiment the applicatorhousing 116 can comprise a separate treatment fluid cartridge which canbe replaced periodically.

Referring to FIGS. 9 and 10 in another embodiment of the invention awiping system is provided wherein the printhead 30 moves back and forthacross a first wiper 124 mounted on the sled 52 and back and forthacross a second applicator wiper combination 128 of specializedconfiguration mounted on the sled on an opposite side of a wickingapplicator nib 122. As the printhead moves to the left in the figuresthe printhead is first wiped by the first wiper, and then contacts arounded applicator portion 129 of the second wiper 128 which haspreviously been dosed with treatment fluid. After passing the transferwiper the printhead direction of travel is reversed and the printheadmoves to the right in FIGS. 9 and 10. The orifice plate 40 is wiped bythe second wiper as the printhead continues to move right. At the sametime the second wiper is deflected in the direction of printhead traveland the rounded applicator portion is bent over and downward to contactthe wicking applicator nib 122 made of a porous wicking material andsaturated with treatment fluid from a reservoir 130 filled with a secondwicking porous media such as an open cell foam or fibrous material asdescribed above. A small reproducible amount of treatment fluid istransferred to the second wiper's rounded applicator portion by thiscontact, and this fluid is available to assist in wiping on the nextwiping cycle. The printhead continues its movement to the right in thefigures and is wiped a second time by the first wiper 124. A scraper(not shown) can be placed on the carriage to clean the wipers by wipingcontact. As can be appreciated the scraper is placed to the right of theprinthead 30 in FIGS. 9 and 10 so as to scrape the transfer wiper onlyafter it has transferred treatment fluid to the printhead.

This embodiment provides an advantage in that the applicator wipercombination 128 acts as an intermediate transfer element to transfertreatment fluid from a source of treatment fluid 73 to the printhead.The result is that the applicator nib 122, and consequently thetreatment fluid 74 is kept cleaner as the printhead 30 is wiped by thefirst wiper just previous to application of treatment fluid by theapplicator/wiper combination 128 and the applicator nib 122 does notdirectly contact the printhead.

With reference now to FIG. 11 in another embodiment a doseableelastomeric applicator 132 having the form of a duckbill mounted on thecarriage 42 beneath a hopper 134 adapted to receive treatment fluid 74from a stationary spigot 136 located at the service station at an end ofthe carriage's range of travel. A similar duckbill-like applicator isshown in FIG. 22. Returning to FIG. 11, as the carriage nears the end ofits range of travel (to the right in FIG. 11) it contacts and depressesa spring-biased plunger 138 actuating a low volume pump 140 furthercomprising a pair of check valves 141 and 142. The configuration andmode of operation of such pumps is well known. A small-volume dose oftreatment fluid is pumped into the hopper and, urged by gravity,migrates to the applicator 132. The applicator is configured to wipinglyengage a wiper set 144 having two wipers 70 adapted to wipe theprinthead 30, and a small reproducible amount of treatment fluid isdispensed at each such contact due to deformation of the elastomericapplicator at each such wiping contact. The wipers can be identical orhave differing configurations to achieve a desired effect when theprinthead is moved past. The motion of the carriage being controlled bythe printer controller (not shown) the dispensing of treatment fluidinto the hopper can be programmed to occur to dose the applicator asneeded to maintain a small amount of treatment fluid in the applicator.For example the carriage can be moved to the limit of travel to dispense1-5 microliters each time the printhead is serviced, or at longerintervals, for example dispensing 1-25 microliters of treatment fluidinto the hopper once every 5 times the printhead 30 is serviced. Acollapsible treatment fluid reservoir 144 is connected to the pump toprovide a leak-proof printer-lifetime supply of treatment fluid.

This embodiment provides the advantage of a carriage-mounted treatmentfluid applicator 132 without having to carry the treatment fluidreservoir 144 on the carriage. Accordingly the doseable applicator 132acts as a transfer element, transferring treatment fluid from a source73 of treatment fluid 74 to the wiper 70. Also, by providing acheckvalve 141 located downstream of the pump 140 with sufficiently highcracking pressure, unwanted fluid leakage from the reservoir, such asmight occur during shipment for example, is prevented. T he amount oftreatment fluid in the hopper 134 is kept small so that leakage from thehopper due to tipping of the printer 10 for example, should it occur, isminimized. Also, the applicator 132 could be replaced by a wicking blockformed of a porous media, which is periodically re-saturated withtreatment fluid as required, to mitigate spilling from the hopper.

Turning to FIG. 12 in another embodiment a composite treatment fluiddosing wiper 146 is provided on the sled 52 for wiping the printhead 30.A section of saturated porous material 148 such as an open-cell foam issandwiched between two elastomeric wipers 150 and 151 of a specializedwiper set comprising the composite fluid dosing wiper. A passageway 152is connected to a source of treatment fluid (not shown) such as acollapsible reservoir, and treatment fluid is drawn into the section ofporous material as fluid is depleted therefrom. Replenishment oftreatment fluid can be by gravity feed, or by capillary attractiveforces in the porous material acting on the treatment fluid for example.Alternatively, the saturated foam is sized to accommodate a printerlifetime supply of treatment fluid. In one embodiment the wiper is widerin a direction transverse to that of wiping motion (out of the plane ofthe page in FIG. 12) and the ends of the wiper are each closed by a wall153 formed unitary of EPDM with the wipers 150, 151 serving to containtreatment fluid in the composite wiper.

In operation, the printhead 30 wipingly contacts the composite dosingwiper 146, and in doing so deforms a first elastomeric wiper 150 andsqueezes somewhat the saturated porous segment 148 causing treatmentfluid 74 to be expelled upwardly onto the second wiper 151. The firstwiper 150 is provided with a ramp portion 154 to assist in easing therelative wiping movement of the printhead 30 over the porous segment 148so that no direct contact between the printhead and the porous segmentoccurs. As a result the foam comprising the porous segment is keptcleaner. The squeezing action of the wiping contact between the dosingwiper and the printhead gives rise to a pumping action which also canassist in drawing treatment fluid upward within the porous layer, aswell as into the composite dosing wiper from the source of treatmentfluid via the passageway 152.

As can be appreciated with reference to FIG. 13 in another embodiment acomposite treatment fluid dosing wiper 146 likewise comprises acomposite construction. An elastomeric outer envelope 156 of EDPMencloses an inner segment of treatment fluid-saturated porous material148 fed by a conduit 152 as described above. A series of small openings158 in the outer envelope are provided from which treatment fluid canemerge when the dosing wiper 146 is deformed in wiping. The opening 158shown in the figure is enlarged for clarity, and as can be appreciatedthe openings are sized to meter the amount of treatment fluid dispensedat each wiping contact of the printhead 30 for example, and canalternatively comprise a series of openings which are normally closedbut open upon deformation of the fluid dosing wiper 146.

Turning now to FIG. 14, in another embodiment of the invention atreatment fluid applicator 132 is positioned within the pen cap 66itself. This allows the orifice plate 40 to be wetted with treatmentfluid open the pen 20 being capped. In the illustrated embodiment theapplicator is of duckbill valve-like configuration and applies treatmentfluid when the treatment fluid within the applicator is sufficientlypressurized to exceed a cracking pressure of the duckbill, as is wellunderstood by those skilled in the art. The orifice plate lightlycontacts the applicator and a small amount of treatment fluid, forexample up to about five microliters, is dispensed onto the orificeplate.

In the illustrated embodiment pressurization is provided by aspring-loaded piston pump 140 actuated by depression of the sled 52 asthe printhead 30 of the pen 20 is capped, the pump being placed betweenthe sled and printer service station structure 50 for example. Theduckbill applicator 132 acts as a checkvalve in operation of the pump. Afurther checkvalve 142 is required for pumping, as is well known, and isplaced in a conduit 152 supplying treatment fluid from a collapsiblefluid reservoir 144 for example. A low volume spray pump (not shown) ofconventional configuration could be substituted, such a pump having itsnozzle projecting upward so as to spray the orifice plate 40 upon thepen being capped.

With reference to FIGS. 15, 16 and 17, in another embodiment of theinvention a printer 10 incorporating a different way of servicing theprinthead orifice plates 40 of the pens 20, 160 is illustrated. A blackpen 20 and a tri-color pen 160 for example are used, carried on areciprocating carriage 42. As will be will be apparent, the discussioncan be applied to other configurations such as a four pen system asdescribed above, as well as to various other types of inkjet printingdevices. It will again be understood that where reference is made to onepen 20, printhead head 30, or wiper 70, etc. the same is understood tobe generally applicable in multiple pen systems and to wiper sets havinga plurality of wipers. The service station 50 incorporates wipers 70which are carried by a rotatable tumbler 162 which rotates about an axisparallel to the reciprocating motion of the pens 20, 160 carried by thecarriage 42 in printing operations. The direction of wiping isaccordingly transverse to the direction of travel of the pens. Thedirection of wiping is aligned with the rows of orifices (not shown) inthe orifice plate 40 from which ink is ejected in printing. Moreover, inone embodiment the wiper is configured with two separate projectingwiping portions 164, 166 which are aligned with and wipe only the areaimmediately adjacent each of the two rows of orifices in the orificeplate. This configuration maximizes wiping effect at critical locationson the printhead. As will be appreciated, the other embodimentsdescribed herein can utilize such a wiper configuration, though forsimplicity a more simplified geometry is shown in the drawing figures.

Also incorporated in the tumbler 162 are caps 66 which are used to capthe pens as described above. The caps can be pivotally and/orspring-mounted on the tumbler to facilitate capping and a consistenttight seal. Provision for vacuum priming is not made in connection withthe tumbler-mounted caps, and in this embodiment the orifice plate 40nozzles are cleared by “spitting” ink into a “spittoon” 168 provided forcatching ejected ink and debris. This spitting operation can beperformed less often in a printer according to the invention due to theprinthead being kept cleaner by increased wiping effectiveness achievedwith use of treatment fluid. In another embodiment (not shown) thetumbler can be made to rise and lower by provision of movable supportsfor the tumbler and an actuation means, for example a worn geararrangement, or a solenoid. This may be done for example in connectionwith capping the printhead 30 or rotating the wipers 70 past theprinthead without contacting it.

With reference particularly to FIG. 17, the tumbler 162 is actuated by adriver gear 169 coupled to a drive motor (not shown). The drive gearengages peripherally disposed gear teeth 171. As can be appreciated, thedrive motor is reversible and is controlled by the printer controller(not shown). The tumbler 162 accordingly can be rotated in eitherdirection at a controllable speed, and reciprocating movement ispossible. Scrapers 170 are provided within the service station to cleanthe wipers. Absorbent pads 172 are disposed adjacent the scrapers tocatch ink, treatment fluid and any debris flung from the wipers as theyrebound after passing by the scrapers as the wipers rotate past them (ina counterclockwise direction in FIG. 17).

The scrapers are moveable closer to and away from the tumbler 162 toengage the wipers 70 as desired, but not the cap 66 for example. Themovement of the scraper is coordinated with rotation of the tumbler byproviding a cam surface 174 on the tumbler 162 and a follower 176coupled to a hinged frame 178 carrying the scrapers. The frame pivotsabout a hinge 180 having an axis parallel to the axis of rotation of thetumbler. A link 182 connected to the cam follower is attached to theframe and in operation pulls a scraper-carrying first end of the frameopposite a second hinged end 181 of the frame closer to the tumbler asrequired for scraping the wipers 70 of a dual wiper set 144. In oneembodiment the hinged frame is biased to a position away from the wiperfor example, and is drawn closer by the cam surface.

The service station also includes a source of treatment fluid 184disposed at the lower portion of the service station 50. This source oftreatment fluid further includes a capillary applicator 109 in fluidcontact with the interior of a closed chamber 78, similar to thatdescribed above, of a treatment fluid reservoir 100 containing a lowvolatility solvent 74 such as PEG described above. The capillaryapplicator 109 illustrated has two elastomeric flap components 190, 191having chamfered portions 189 adjacent the upper tip 114 and planaropposed surfaces 192, 193 separated by a capillary space 112therebetween. As described above, fluid rises in the capillary space toa tip portion 114. The applicator is formed of EDPM having a durometerof 70. The elastomeric flaps 190, 191 of the specialize applicator 109are provided with hinge portions 194, 195 near their bases which allowthe two halves of the upper part of the applicator to separate somewhat.This allows more treatment fluid to congruent at the upper portion byspreading the capillary wider in this area. In the illustratedembodiment the two elastomeric flaps are substantially identical.However, in another embodiment they can be given differing geometries,for example to provide a particular desired functional property.

Each of the flaps 190, 191 have identical geometries, simplifyingassembly. For example in one embodiment each flap is four millimetershigh measured from stabilizing wings 196, 197 disposed at their bases,and are one millimeter thick. The chamber portion 189 is threemillimeters in height and has a thickness at the tips 114 of each flapof 0.2 millimeters. The width of the flaps (perpendicular to the planeof the page in FIG. 17) is at least as wide as the portion of theprinthead to be wiped. The capillary space should be small enough sothat there is a relatively higher attractive force associated therewith,and hence a capillary gradient from the reservoir 100 disposed below,sufficient to draw treatment fluid upwards into the capillary space.

The chamber 78 of the reservoir 100 is formed by a containment 186formed in the service station 50 and a lid 187. The lid has an opening188 through which the applicator protrudes. The enclosed interior volumeis filled with an open-cell foam material, fibrous or otherwise porousmaterial comprising a porous media wicking block 110 impregnated withtreatment fluid. One or more small vents 79 are provided to admit airfrom near the bottom of the chamber 78 as treatment fluid is depletedfrom the reservoir. This arrangement is similar to that described abovein that the fluid is retained in the reservoir by capillary attractionduring shipping, etc. but is available to the wiper as required. In oneembodiment the wicking block employs a polyurethane foam or othertreatment fluid-compatible material having a pore size, pore volume, andcapillary fluid attractive properties compatible with the applicator109. In this regard the pores must be sufficiently large, even whencompressed by the applicator as illustrated, and the foam propertiesotherwise selected so that a capillary gradient between the reservoir100 and the applicator 109 tends to draw fluid upwards as discussedabove.

As will be appreciated, the foam or other porous media comprising thewicking block 110 within the reservoir 100 is compressed somewhat at alocation directly adjacent the applicator 109 as the applicator furthercomprises stabilizing wings 196 and 197 which protrude into and impingeupon the wicking block 110, reducing pore size at that location.Accordingly localized higher capillary forces within the wickingmaterial will tend to draw treatment fluid toward the compressed areaand make it available to the applicator at its base, to be drawn intothe capillary space within the applicator and migrate to the upper tipportion 114.

Treatment fluid in a small reproducible quantity is transferred from thetip 114 to each wiper 70 as the wiper wipingly contacts the applicator109 as it rotates past. After passing each of the wipers by theapplicator for example, the wiper set 144 rotated around to the orificeplate 40 of a carriage-mounted pen 20 positioned for servicing and wipesthe orifice plate. As mentioned, after wiping each wiper is cleaned bythe scraper 170 as it passes by in wiping contact therewith. Thisprocess can be controlled according to a preprogrammed sequence by theprinter controller, or in response to an operator-initiated cleaningsequence.

The source of treatment fluid 184 can take other forms. Referring toFIG. 18 for example, the illustrated embodiment comprises a capturedblock 200 of compliant open-cell elastomeric foam, having an exposedsurface 202 which is wiped by the wiper 70. The captured block acts bothas a reservoir and an applicator. The treatment fluid is retained in thefoam by capillary forces as before described. In addition to theabove-mentioned advantages in storage and transport obtained, it hasbeen found that in this embodiment a “pumping” action in the foamoccurring due to deformation by the passing wiper tends to wash thewiper and the exposed surface of the foam reservoir and bring newtreatment fluid to the surface of the foam block, thereby dissipatingsomewhat deposits of ink left by the passing wiper that may otherwiseaccumulate at the exposed surface 202.

In a further embodiment a protective layer 204 of a differing materialis placed over the exposed surface portion 202 of the foam. The layerserves to protect underlying foam or, alternatively, another porousmedia, from abrasion occasioned by the wiping contact of the wiper 70.The protective layer also serves a metering function if the porosity ofthe protective layer material is controlled to allow only a desiredamount of treatment fluid through due to pumping action during each passof the wiper, and also can be made to act to regulate the amount offluid transferred to the wiper by providing a textured surface wiping ordrawing excess fluid from the wiper as it passes. Depending on roughnessof the surface 202 the protective layer 204 can also perform a wiper 70cleaning function, removing dried ink accumulations for example as thewiper wipes the protective layer. The protective layer in one embodimentis made of a woven material such as polymeric filament or stainlesssteel wire fabric or metals, or a porous layer of another wear-resistantmaterial, for example a more wear-resistant foam layer as describedbelow, or a porous sheet of plastic or metal material which allowsmigration of treatment fluid therethrough. Such a sheet may be formedfor example by a sintering process, or by ablating holes in a non-poroussheet. The relative wetting and pore size characteristics of thecompliant foam block 200 comprising the fluid reservoir 100 and those ofthe protective layer 204 are controlled so that treatment fluid is drawnto the surface 202 to be available to the wiper by capillary action, orby the pumping action of the passage wiper, or some combination thereof.

In one embodiment the protective layer 204 is a nylon mesh, having apore size small enough to retain the selected treatment fluid bycapillary and attractive forces in the mesh. The mesh is disposed over aPEG-impregnated polyurethane foam. In another embodiment the protectivelayer is a stainless steel mesh. In either embodiment it has been foundthat the pore size of the mesh can be larger or smaller than that of thefoam.

Referring to FIG. 19 in another embodiment a foam laminate is createdhaving a protective layer 204 of relatively rigid foam on top of a morecompliant open-cell foam block 200 comprising the treatment fluidreservoir 100. Again in this embodiment the pore size and wettingcharacteristics are controlled to obtain the results desired. In oneembodiment for example the top layer is a relatively stiffer porouspolypropylene foam having a pore size of approximately one hundredmicrons and a pore volume of about forty percent. The underlying fluidreservoir foam is a polyurethane foam having a pore size greater thanthat of the upper layer so as to provide a capillary gradient tending todraw treatment fluid upwards from the bottom layer to the upper surface202 of the reservoir.

With reference to FIG. 19A, a further reservoir/applicator embodimentcomprises a captured block of compliant open-cell foam 200 partiallyexposed to the wiper 70 to be wiped thereby as discussed above, and alayer of stiffer foam 205 which overlays a part of the foam block 200.The stiffer foam is disposed at an angle to the portion of the open cellfoam block 200 exposed to the wiper so as to be contactable by the wiper70 the compliant foam is first wiped, bringing treatment fluid to theexposed surface 202 and transferring it to the wiper subsequently thestiffer foam is wiped as it continues to rotate, for example by actionof a tumbler (not shown). This embodiment provides the advantage of thepumping and wiper washing action discussed above in connection with theopen cell foam, as well as improved cleaning and meteringcharacteristics of the stiffer foam layer 205 which the wiper contactsafterward. Ink residue for example is retained in the stiffer foamlayer, while treatment fluid can pass through to the underlying opencell foam block 200 to again be available to be applied to the wiper.

Referring to FIG. 20, in another embodiment the fluid reservoir 100comprises a porous media such as a fibrous bundle 206 impregnated withPEG contained within a porous sintered plastic cylindrical shell 208supported by the service station 50. In this embodiment the cylinderformed of sintered plastic can be periodically rotated for example bycontact of the wiper, or only as it becomes contaminated with ink.Alternatively the cylindrical reservoir can be held stationary, forexample by a set screw 210 as shown or by mechanical interference,adhesive, or sonic welding. The fibrous bundle reservoir is formed ofconventional materials, such as are readily commercially available andadapted to use in forming fluid reservoirs, for example in marker pensand the like. The fibers are bundled parallel within a sinteredpolymeric resin cylinder having pore size and wetting properties so asto provide a capillary gradient from the fibers inside tending to drawtreatment fluid up into the cylinder and onto its outer surface.

In another embodiment, illustrated in FIG. 21, a layered foam reservoir100 as described above is fitted with a remvoable protective cover. Thecover comprises for example a flap 212, which closes onto the upperprotective layer 204. This protective layer a layer of relatively hardfoam as shown, or a plate with holes ablated or sintered therein asdescribed above, to improve performance of the reservoir. The cover whenclosed provides a capillary space between the cover and protective layerwhich assists in wicking of the treatment fluid up and out of the upperlayer surface 202 so as to be available to the wiper and also helps keepthe upper surface clean by protecting it from ink and debris between penservicing operations. This embodiment otherwise functions as beforedescribed in connection with layered reservoirs.

As can be appreciated, in each of the embodiments of FIGS. 18-21 thetreatment fluid reservoir 100 also acts as an applicator, transferringtreatment fluid to the wiper 70 when wipingly contacted thereby. Thisconfiguration gives advantages in simplicity of fabrication and reducedcosts of manufacture.

With reference to FIG. 22, another way of metering treatment fluiddispensed is to actually control the amount of fluid available by directmechanical means. In the embodiment shown this is accomplished byproviding a stationary duckbill checkvalve applicator 132 carried by theservice station 50 which is contacted by the wiper 70. The amount oftreatment fluid made available to the wiper at an upper tip 214 of theapplicator is metered by the action of a small volume syringe pump 216controlled by the printer controller. As can be appreciated a controlledamount of treatment fluid is expelled from the duckbill applicator tipwhen fluid pressure exceeds a cracking pressure threshold of theapplicator due to displacement of fluid for example by a smallincremental movement of a syringe piston 218 of the pump fluidlyconnected thereto as shown. The piston can be actuated for examplethrough a conventional screw drive activated by a stepper motor (notshown). Alternatively, a peristaltic pump or other finely controllablepump capable of administering fluid in volume increments of one to fivemicroliters for example could be used. In the illustrated embodimentcheckvalves 141, 142 are provided to allow the piston 218 to reset aftereach stroke, drawing treatment fluid from a collapsible treatment fluidreservoir 220 as shown. In an alternate embodiment the syringe pump issized to accommodate a printer lifetime supply of treatment fluid. Sucha pump could be actuated for example by a ratcheting drive mechanismcoupled via a reduction gear set to the tumbler accordingly dispensingof the treatment fluid can be both activated by and coordinated withtumbler rotation in wiping.

Referring to FIG. 23 in another embodiment the treatment fluid source184 incorporates a transfer element 222, in this case an elastomerictransfer wheel roller rotatable about an axis parallel to that of thetumbler (perpendicular to the plane of the page in FIG. 23), to transfertreatment fluid from a treatment fluid reservoir 100 to the wiper 70.The roller must be as wide (in a direction perpendicular to the plane ofthe page in FIG. 23) as the portion of the wiper 70 to be wetted. Thereservoir includes a porous media 110 to retain the treatment fluid inthe reservoir without leaking as described above, and this materialtransfers treatment fluid to the transfer roller 222 in contacttherewith as the roller rotates. Alternatively, a free fluid reservoircould be used, provided mitigation of leaking due to tipping of theprinter or pressure changes is also provided as discussed elsewhereherein.

In operation, treatment fluid is brought upward from the reservoir 100to be available to the wiper 70 by rotation of the transfer roller. Thisrotation can be solely by means of wiping contact of the wiper in oneembodiment, which wiping contact rotates the transfer roller a part ofone rotation at each pass and makes fresh treatment fluid available onits surface to be transferred to the wiper on the next pass. In anotherembodiment the roller is rotated by a drive motor (not shown) coupledthereto and rotation is controlled by the printer controller andcoordinated with rotation of the wiper to dispense a small reproducibleamount of treatment fluid to be transferred to the wiper 70 for wiping.

A cantilevered metering wiper 224 can be employed to further control theamount of treatment fluid on the roller surface to be picked up by thewiper 70, by wiping off excess treatment fluid. As will be appreciatedthe metering wiper, which is shown bending upward to contact the rollerin FIG. 23, can instead be bent downward, facilitating easer assembly inmanufacturing. A transfer wheel scraper 225 is provided, formed unitarywith the containment 186, which acts to remove containments from thetransfer wheel 222. These features combine to reduce contamination ofthe treatment fluid in the reservoir 100. The transfer wheel shownincorporates a layer 223 made of a solid elastomeric material. As willbe appreciated the transfer wheel could also be formed of a foammaterial, or an elastomeric foam material with anon-porous outer surfaceif a softer non-porous wheel is desired.

With reference to FIG. 24 in another embodiment the transfer wheelroller 222 is configured to transfer treatment fluid directly to theprinthead 30. The transfer wheel is mounted so that up-and-down movementis possible, in this embodiment provided by up and down movement of asled 52 on which the wheel is mounted or by provision of a gimbal mount(not shown), or as shown by allowing movement of the wheel in thevertical direction by providing a slot in a containment 186 into whichan axle 228 carrying the transfer wheel fits. The resilience of atreatment fluid saturated wicking block 110 formed of an elastomericopen-cell foam for example urges the transfer wheel element upward afterbeing vertically depressed. A cap 229 defines an opening 232 configuredto limit upward movement of the transfer wheel and allow a portion ofthe wheel to protrude so as to be available to contact the printhead 30.Also, the wheel or roller itself can incorporate a layer of foam orotherwise made compressible allowing some variation in the verticalextension of the transfer wheel 222.

In the illustrated embodiment of FIG. 24 the printhead 30 travels alongits axis of motion towards a portion of the service station 50 where itis pre-wiped by a first wiper 230, then treatment fluid is applied tothe orifice plate 40 as the printhead moves past the transfer wheelroller 222 in contact therewith, and a second wiper 231 wipes theprinthead and removes excess treatment fluid and remaining accumulationsof dried ink, etc. Alternatively, just one wiper can be provided. In thelater case the printhead would be pre-wiped by one wiper 230, thencontacts the transfer wheel roller 222, then reversing directions movetowards and be again wiped by the same single wiper 230.

Referring to FIG. 25, in another embodiment the transfer wheel roller222 is combined with a fluid reservoir 100 wherein a wicking block 110of open-cell foam is doubled back and crimped somewhat at the location24 of contact with the transfer roller. The reservoir is mounted on tieservice station 50. As will be appreciated the pores of the materialbeing compressed are smaller at the location of contact and higherattractive forces there tend to draw treatment fluid towards thelocation as discussed above to be available to the transfer roller. Atumbler 162 with a wiper set 144 provided to wipe the printhead 30 inoperation contacts the transfer roller to transfer treatment fluid toeach of the wipers 70 and also rotates the transfer roller to maketreatment fluid available to the wiper at the next pass. Alternativelythe roller can be driven by a separate drive motor as discussed above. Atransfer roller scraper 225 is provided at the bottom of the transferroller in this embodiment and excess fluid and debris removed from thetransfer wheel by the scraper can fall away from the reservoir 100reducing contamination thereof.

As mentioned, the embodiments shown in FIGS. 23, 24 and 25 can employ asolid or porous wheel roller 222. In another embodiment the transferroller, if made of foamed material, could act as its own treatment fluidreservoir, having a printer lifetime supply of PEG for example containedtherein.

Advantages obtained by use of a transfer wheel roller element 222between the treatment fluid reservoir 100 and the wiper 70 includereducing contamination of the treatment fluid reservoir 100, andproviding a metering function. For a given treatment fluid the amounttransferred to the printhead 30 or wiper 70 can be varied for example byvarying the roughness of the surface of the roller contacting the wiperor printhead 30, the wetting properties of materials used, for appliedin contact of the wheel with other elements, and the use or not of ametering wiper 224 and the stiffness the metering wiper.

With reference to FIG. 26 in a further embodiment of the inventionemploying a transfer element for transferring treatment fluid from afluid reservoir 100 to the wiper 70, a filament element 236, comprisingeither a single strand, such as a nylon wire for example, or a wovenmaterial such as a small diameter nylon rope for example, could beutilized as the transfer element. The filament is held taught and ispressed into a slit 238 in a PEG-saturated open-cell foam block 110contained and supported by the service station 50, and then withdrawn,in this example by action of a cam 239. A spring (not shown) can be usedto tension the filament and allow its displacement by the cam.Alternatively the filament could be placed in a spring-biased hingedframe (not shown) moved by the cam. The filament thus picks up a smallreproducible amount of treatment fluid and the wiper 70 subsequentlywipingly contacts the filament so that a small amount of treatment fluidis transferred to the wiper. This method of transferring and applyingtreatment fluid is advantageous in that the amount of fluid transferredis very controllable. As can be appreciated, the filament dosing methoddescribed could also be adapted to apply treatment fluid directly to theprinthead.

Referring to FIG. 27 in another embodiment where the treatment fluid istransferred to the wiper, the functions of scraping the wiper 70 andtransferring and applying treatment fluid are combined in a corrugatedsurface 240 on each of first and second inclined portions 242, 244 ofthe service station 50 together forming a path 246 comprising anapplicator. Before wiping at least one surface 240 is wetted withtreatment fluid, for example that corrugated surface associated with thefirst inclined portion 242. The parallel ridges and grooves forming thecorrugations serve to clean the wiper as it passes, and ink and debriscleaned from the wiper are trapped in grooves between ridges of thecorrugations. In one embodiment the corrugations are configured so thatfluid can drain over the corrugations. In another embodiment thecorrugations are configured so that fluid pools between corrugations andin the later case the corrugations can be inclined at an oblique angleto the direction of motion of the wiper so fluid can drain to one side.After the wiper passes, excess treatment fluid scraped from the wiper bythe corrugations carries contaminants down to the bottom of the pan 246.

In the illustrated embodiment a piston pump 140, such as described abovefor example is actuated by a cam 248 incorporated in the tumbler 162 andpumps treatment fluid from a collapsible reservoir 220 onto thecorrugated surface 240 of the first inclined portion 242. The pumping offluid is thus controllable by the printer controller (not shown) by wayof rotation of the cam of the tumbler 162 in either direction. Pumpingis coordinated with wiping so that fluid is present on the corrugatedsurface of the first inclined portion when the wiper 70 wipinglycontacts it.

The pan 246 can have a closed bottom (not shown) so that ink and debriscollect and dry there, or could be plumbed to drain into an absorbentmedia 250 for example. In another embodiment the pan is plumbed forrecycling of the treatment fluid, for example by providing aflow-backchecked drain conduit 252 connected to a sludge trap 254 andthe reservoir 220. As can be appreciated, the reservoir in thisembodiment is located at a lower elevation than the pan. A furthercheckvalve 253 is provided to prevent retrograde flow of treatment fluidback into the pan 246.

With reference to FIG. 28, an another embodiment a fluid reservoir 100filled with a porous media as described above is located adjacent thepan 246. A deformable portion 256 of a containment 258 is contacted andsqueezed by the wiper 70 as the wiper passes by, providing a pumpingaction pushing fluid out of the reservoir. The pumping action makestreatment fluid available to the wiper at an opening 260 in thecontainment located so as to be swept by the wiper. A deformable wickingapplicator 80 such as described above can be placed in the opening tocontact the wiper. Otherwise operation of this embodiment is asdiscussed above. In an alternate embodiment a deformable tube segment(not shown) could be substituted for the deformable portion 256, thewiper or another element (not shown) carried by the tumbler acting topump fluid therethrough by deforming contact with the deformable tubesegment tending to sweep treatment fluid in the segment in the directionof wiper movement.

With reference to FIGS. 29 and 30 in a further embodiment of theinvention a treatment fluid 75 is chosen so as to be in a non-flowablestate at ambient temperature, taking into account a range oftemperatures anticipated to be encountered during shipment and use of aprinter 10 incorporating the wet-wiping system of the present invention.The treatment fluid is heated so that it melts to a fluid state forprinthead servicing. The treatment fluid used in this embodiment is ahigh molecular weight PEG, e.g., PEG 1000 or above, stored in solidform. This treatment fluid material at room temperature is a solid waxymaterial. It has been found that mixing PEGs of different molecularweights allows customization of the melting point and hardnessproperties of the material at various temperatures as desired. It hasbeen found that a PEG of 1450 molecular weight works well in thisapplication. This embodiment has particular advantage in storage andtransport of the printer 10, and can be combined with other featuresherein described to optimize performance and minimize problemsassociated with tipping and pressure differences noted. For example, thePEG treatment fluid 75 can be kept in a solid form unless the printer isupright in normal use.

In another embodiment the treatment fluid 75 can comprise a treatmentfluid, such as PEG of lower molecular weight for example, liquid atambient temperature, micro-encapsulated and dispersed within a wax orwax-like material which is solid at ambient temperature. When melted,such a material release the treatment fluid. Moreover, in anotherembodiment the wax-like material can be a high molecular weight PEG andthe encapsulated liquid can be another treatment fluid, for example onewhich has low solubility in PEG, and this other treatment fluid isdispersed and entrained in liquid PEG at an elevated temperature, forexample by high-shear mixing. After cooling the mix the liquid treatmentfluid is micro-encapsulated in a solid PEG matrix.

Heating the treatment fluid to liquify it before use in servicing aprinthead 30 can be done in a number of ways. In one embodimentillustrated by FIG. 29 the solid treatment fluid is liquified bycontacting a block of the solid treatment fluid 75 directly to a heatedorifice plate 40 prior to wiping. A small reproducible amount oftreatment fluid melts and is deposited on the orifice plate. Asmentioned above the contact is located adjacent a side of the printhead30 so that the wiper (not shown) will first contact the treatment fluid,then wipe across the orifice plate. As shown schematically, the block ofsolid treatment fluid 75 is spring-mounted with respect to a verticallymovable sled 52 for example to provide a relatively constant contactpressure, and a rachet 262 can be provided to compensate for reductionin length of the block as treatment fluid is melted off over the printerlife. For example in one embodiment (not shown) a drive shaft from adrive motor actuating the tumbler is coupled by a set of reducing gearsto a ratchet so that the block of solid treatment fluid is indexedtoward the wiper.

Alternatively, as illustrated in FIG. 30 a block of solid treatmentfluid 75 supported by the service station 50 is contacted by a wiper 70or another transfer element. Some solidified treatment fluid is scrapedoff onto the wiper for example, and transferred to the heated orificeplate 40 where it melts due to the elevated temperature of the orificeplate. Treatment fluid is then available and pushed ahead of the wiperto assist in wiping as before described. Provision for a relativelyconstant contact pressure between the wiper and the block of solidtreatment fluid is provided by spring-mounting the block and providing aratchet 262 in this embodiment as well.

In another embodiment shown in FIG. 31 the solid treatment fluid 75 isstored in a reservoir 100 incorporating a heating element 264 connectedto a power source 266 controlled by the printer controller 94. Theheater heats and melts the treatment fluid appropriate times in responseto signals from the printer controller. The reservoir incorporates atransfer element 222 in the form of a roller formed of an elastomericmaterial. The roller material can be solid or porous depending upon thespecific application. The roller protrudes from a containment 186carried by a service station sled 52 for example which can be moved upand down as desired to bring the transfer roller to a positioninterfering with the motion of travel of a printhead 30 to contact theprinthead orifice plate 40 as before described. As can be appreciatedthe reservoir is a free fluid reservoir when the heated treatment fluidis in liquid state and treatment fluid is transferred to the orificeplate by the roller as before described. After application of treatmentfluid to the printhead orifice plate it is wiped, for example by a setof wipers 144 positioned nearby. A metering wiper 224 and a transferwheel scraper 225 function as described above and also assist incontacting treatment fluid within the free-fluid reservoir when in aliquid state. The transfer wheel could be rotated by a drive motor (notshown) or be turned by the wiping contact of the printhead 30 in thisembodiment in incremental partial rotation as heretofore described.

As shown in FIG. 32, in another embodiment a fluid reservoir 100,similar to that described in connection with FIG. 31 containing a highmolecular weight PEG and a heater, is positioned in a service station 50so as to be wiped by a tumbler-mounted wiper 70 which subsequently wipesa printhead 30, rather than contact the printhead directly as in theembodiment of FIG. 31.

In further embodiments shown in FIGS. 33, 34, and 35 a treatmentfluid-carrying tape is used to apply treatment fluid to the printhead 30or wiper 70. With reference to FIG. 33 in one embodiment the source 184of treatment fluid used in wiping the printhead orifice plate 40 of theprinthead 30 comprises a roll of treatment fluid impregnated lint-freefabric layer 268 which tape is advanced as required to make freshtreatment fluid available to the wiper 70 which first contacts the tapeand subsequently wipes the printhead. The treatment fluid carried by thetape could be PEG in a liquid or solid form. The tape is conventionallywound on a supply reel 272 and a take-up reel 274 which areincrementally turned as directed by the printer controller (not shown).As can be appreciated the tape 268 can be stored in a cassette 276having a window 278 allowing access to the tape by the wiper, and such acassette could be replaceable. The tape in one embodiment is formed of alint-free cloth such as described below, but could be formed of othermaterials, for example a flexible tape having a roughened surfaceadapted to retain treatment fluid thereon.

In another embodiment shown in FIG. 34 a fabric tape 268 could be madeto contact the printhead 30 directly for cleaning. In this embodimentthe fabric tape itself assists in cleaning as it is moved over theorifice plate 40, and as can be appreciated the texture of the fabric ischosen to increase cleaning effectiveness. In one embodiment lint-freeribbon material such as that used to sore ink in dot-matrix printers andtypewriters for example, and known in the art is employed. In anotherembodiment a lint-free cotton material such as TX 309 TEXWIPE or theequivalent is used. TEXWIPE is a trademark used by Texwipe Incorporatedof Upper Saddle River, New Jersey. A padded pressure plate 270,vertically actuated by means of a cam 280 for example, can be used tobring the fabric tape into contact with the orifice plate. Again thetape could be contained in a replaceable cassette 276 having a tapeaccess window 278.

With reference to FIG. 35 in another embodiment a continuous lop of alint-free fabric tape 268 such as described above is used to applytreatment fluid to the orifice plate 40 of a printhead 30, and againperforms a cleaning function in addition to transferring treatment fluidto the printhead. In this embodiment the fabric loop is disposed onrollers 281 supported by the service station 50 and driven by a transferwheel roller 222 turned by a shaft 282 coupled to a drive motor (notshown) controlled by the printer controller. The transfer wheel is in atreatment fluid bath 284, comprising for example a high molecular weightPEG which is heated for use, but otherwise is in solid form preventingleakage from tipping etc. As will be apparent, the transfer wheel couldalternatively be wetted as described above in connection with FIGS. 23,24, 25, or 31 for example. Returning to FIG. 35 a padded pressure plate270 is vertically movable by a hydraulic actuator 286 to bring thefabric tape into and out of contact with the orifice plate. Toaccommodate vertical deflection of the fabric tape, and maintain aconstant tension on the fabric tape, a spring-biased tensioner 288 isconventionally provided.

Turning now to FIGS. 36-39, in a further embodiment of the invention ametered amount of treatment fluid 74 is applied directly to theprinthead 30 by throwing or projecting it through the air from aprojecting means onto the orifice plate 40. An advantage of such asystem is that the source of treatment fluid is not contaminated bycontact with a wiper 70 or the printhead.

Referring to FIG. 36, in one embodiment a low-volume mechanical spraypump 290 carried by the service station 50 is actuated, for example by acam or solenoid (not shown), to spray a metered dose of one to fivemicroliters of treatment fluid onto the orifice plate as it passes by oris stationed over a sprayhead 292 of the pump. Treatment fluid is storedin a collapsible fluid reservoir 220 fluidly connected to the pump via afluid conduit 152 in this embodiment. The treatment fluid is PEG ofmolecular weight 200-600 in this embodiment.

With reference to FIG. 37, in another embodiment the treatment fluid 74is thrown or projected onto the printhead by a thermal jetting processin the same way as ink is projected in well-understood thermal inkjetprocesses used in printing. An inkjet-like cartridge 294 having acollapsible treatment fluid reservoir 296 and a conventional thermalprinthead 298 connected to a power supply 300 is positioned, for exampleon a service station sled 52, so as to be able to project treatmentfluid onto the pen printhead as desired, the jetting of treatment fluidbeing controlled by the printer controller 94 and coordinated with themotion of the printhead 30 passing by or stationed over the treatmentfluid-projecting printhead 298. The cartridge is filled with a jettabletreatment fluid, for example one-half PEG of between 200 and 600molecular weight, and one-half water. As can be appreciated, apiezo-electric ink jetting cartridge, also otherwise conventional, canbe used instead of a thermal system. An advantage of this embodiment isthat treatment fluid can be metered, for example by counting dropsejected as is known in the art to provide an optimal dose of treatmentfluid.

Turning to FIGS. 38 and 39 in another embodiment of the invention thetreatment fluid 74 is thrown or projected toward the printhead 30 by aspring steel “flipper” 302 cantilever-mounted on the service station 50adjacent a tumbler 162 having a relatively stiff transfer wiper 304mounted thereon. A treatment fluid source 184, for example comprising amesh-covered foam reservoir 100 as described above, is positioned to becontacted by the transfer wiper as the tumbler is rotated. Otherreservoir embodiments described herein could be substituted for themesh-covered foam reservoir shown. As the tumbler 162 is rotated a smallreproducible quantity of treatment fluid is picked up by the transferwiper 304 as it wipes the mesh-covered foam treatment fluid reservoir100. This quantity of treatment fluid is transferred to the spring steelflipper 302 as the transfer wiper rotates around and contacts theflipper. The flipper is elastically deflected downwardly, and scrapesthe tumbler mounted transfer wiper clean of treatment fluid as thetransfer wiper continues to rotate past. As can be appreciated, when thetransfer wiper clears the flipper the flipper is released and reboundsupwardly, flinging a reproducible portion of the treatment fluid upwardand onto a printhead 30 to be serviced, the printhead being positionedat a first position above the flipper for this purpose.

After the treatment fluid 74 has been thrown onto the printhead 30 theprinthead is moved along its axis of travel to a second position to bewiped by an offset tumbler-mounted wiper 70. This is best appreciatedwith reference to FIG. 39.

With reference to FIG. 40, in another embodiment the spray pump,treatment fluid jet, or flipper described above can be used to applytreatment fluid to the wiper instead of the printhead directly. As anexample, a service station-mounted PEG-jetting cartridge 294 asdescribed above and controlled by the printer controller 94 isconfigured to spray treatment fluid onto a wiper 70 prior to wiping theorifice plate 40. The advantages with regard to metering treatment fluidamounts, and preservation of the cleanliness of the source of treatmentfluid are obtained in this embodiment as well. As can be appreciated aseparate service station-mounted scraper 170 as described above can beprovided.

With reference to all the embodiments described herein the applicationof a treatment fluid in the printhead wiping process add one moreparameter (the treatment fluid itself) that can be varied to keep theprinthead 30 clean, resulting in better print quality over the life ofthe printer 10, and lower operating costs and reduction of wastedresources due to improper printhead function attributable to inadequatecleaning, particularly where pigment-based, quick drying and waterfastinks are employed. By machining the chemical and physicalcharacteristics of the ink, orifice plate surface 40 and wiper 70 with acomplementary treatment fluid, optimization of pen cleanliness, wiperlife and servicing speed is possible. These considerations areespecially important if a given printhead is used for a long period oftime. Moreover, the results of the invention can be obtained usingconfigurations that are maintenance-free throughout the life of theprinter 10. These considerations result in overall improved performanceat tow additional cost to purchasers.

Persons skilled in the art will readily appreciate that variousmodifications can be made from the presently preferred embodiments ofthe invention disclosed herein and that the scope of protection isintended to be defined only by the limitations of the appended claims.

1. A method of servicing an inkjet printer printhead comprising thesteps of : providing a wiper mounted for movement with respect to theinkjet printer printhead in wiping contact therewith to remove unwantedaccumulation from the printhead; providing a source of printheadservicing fluid; providing another inkjet printhead as a non-contactservicing fluid applicator and orienting said applicator to jetservicing fluid in a reproducible quantity onto a surface of theprinthead of said inkjet printer and the wiper; transporting servicingfluid from said source to said applicator; jetting a reproduciblequantity of servicing fluid from said an inkjet printhead used as aservicing fluid applicator through atmosphere onto at least one of theprinthead of said inkjet printer and the a printhead wiper; andwipingcontacting the printhead of the inkjet printer by movingwith thewiper during relative movement of the wiper with respect toand theprinthead of the inkjet printer to remove unwanted accumulationtherefrom; vaporizing said servicing fluid to jet ejecting said fluidfrom said applicator printhead; and said servicing fluid being projectedfrom said applicator printhead onto the printhead and said wiper; and ;counting drops of servicing fluid ejected from said applicator head ;and controlling the amount of servicing fluid applied to the printheadbased on the counted number of drops.
 2. The method of claim 1, furthercomprising the steps of : maintaining said a source of servicing fluidin an uncontaminated state by preventing contact between said source ofservicing fluid and said wiper.
 3. A method of servicing applyingservicing fluid to a printhead of an inkjet printer printing mechanismcomprising the steps of : providing a wiper mounted for movement withrespect to the printhead to facilitate removing unwanted accumulationsfrom the printhead; providing a source of printhead servicing fluids;providing a non-contact applicator and orienting said applicator toproject servicing fluid in a reproducible quantity onto a surface of atleast one element selected from a group consisting of two elements, theprinthead and the wiper through surrounding atmosphere; transportingservicing fluid from said a source to said a non-contact applicatorcomprising a resilient spring; projecting the servicing fluid throughthe atmosphere from said spring onto said at least one element of saidprinthead and a printhead wiper; and wiping the printhead by moving thewiper with respect to the during relative movement of said wiper andprinthead to remove unwanted accumulations from the printhead, saidnon-contact applicator comprising a spring; and said servicing fluidbeing projected by: deforming said applicator spring; and releasing saidapplicator spring to project servicing fluid from said spring onto saidprinthead by rebound of said spring.
 4. A system for servicing an inkjetprinter having a printhead reciprocally moved by a carriage and a wiperpositioned to move with respect to the printhead in wiping contacttherewith to remove unwanted accumulations, comprising: a source ofprinthead servicing fluid; a servicing fluid applicator for projectingservicing fluid through the atmosphere onto at least one of theprinthead and wiper; and means for transferring servicing fluid fromsaid source of servicing fluid to said applicator, wherein saidapplicator comprises an elastically deformable spring for impellingtreatment servicing fluid toward at least one of the printhead andwiper.
 5. A system method according to claim 4 15, wherein saidapplicator second printhead is oriented to project a preciselycontrollable amount of servicing fluid through atmosphere onto aselected area on the printhead of said inkjet printer and said wiper thefirst printhead; and wherein said means for transferring servicing fluidincludes: control means for counting drops of servicing fluid propelledfrom said applicator second printhead to help facilitate controlling theamount of servicing fluid applied to the inkjet printer first printheadbased on the counted number of drops.
 6. The system method of claim 4 5,wherein said applicator head includes second printhead is a thermalinkjet head in fluid communication with said source .
 7. The system ofclaim 6, further comprising a counter coupled to said applicator headfor counting drops of servicing fluid ejected therefrom to control theamount of servicing fluid applied to the printhead.
 8. The system ofclaim 4, wherein said spring is cantilever-mounted and positioned tothrow treatment onto said at least one element .
 9. The system of claim8, further comprising a transfer wiper for placing servicing fluid fromsaid source onto said spring by wiping contact, said transfer wiperbeing positioned to elastically bend said spring away from said at leastone printhead and wiper element and then release said spring.
 10. Asystem according to claim 4, wherein said applicator includes: acartridge for storing said reservoir of treatment fluid; and saidapplicator head being in fluid communication with said cartridge forjetting a desired volume of said treatment fluid onto said printheadorifice plate to facilitate an improved wiping action.
 11. A systemmethod according to claim 10 16, wherein said cartridge second printheadis a refillable cartridge.
 12. A system method according to claim 10 11,wherein said applicator head second printhead is a thermal fluid jettingprinthead.
 13. A system method according to claim 10 11, wherein saidapplicator head second printhead is a piezo-electric fluid jettingprinthead.
 14. A method of servicing a portion of a printhead of aninkjet printer comprising the steps of: providing a wiper mounted formovement with respect to the printhead in wiping contact therewith toremove unwanted accumulation from a portion of the printhead; providinga source of printhead servicing fluid; providing another inkjetprinthead as a non-contact servicing fluid applicator and orienting saidapplicator to jet servicing fluid in a reproducible quantity onto asurface of the printhead of said inkjet printer and the wiper;transporting servicing fluid from said source to said applicator;jetting service fluid from said applicator through atmosphere onto theprinthead of said inkjet printer and the wiper; and wiping the printheadof the inkjet printer by moving the wiper with respect to the printheadto remove unwanted accumulation therefrom; and further comprising thesteps of: vaporizing said servicing fluid to jet ejectingly said fluidfrom said applicator printhead; and said servicing fluid being projectedfrom said applicator printhead onto the printhead and said wiper.
 15. Amethod of servicing a first inkjet printhead comprising: using a secondprinthead to project a reproducible quantity of servicing fluid throughatmosphere onto said first printhead; and wiping said first printhead toremove unwanted accumulation.
 16. The method of claim 15, comprisingthermally projecting said servicing fluid.
 17. The method of claim 15,comprising piezo-electrically projecting said servicing fluid.
 18. Asystem for servicing a printer having a carriage mounted inkjetprinthead on a reciprocally movable carriage and a wiper positioned towipe the carriage mounted printhead to remove unwanted accumulationsfrom the printhead, a source of printhead servicing fluid, a non-contactservice fluid applicator in fluid communication with said source, saidnon-contact applicator comprising a second inkjet printhead oriented toeject servicing fluid in a reproducible quantity onto a surface of saidcarriage mounted printhead.
 19. A method of servicing a portion of ascanning printhead of an inkjet printer which includes a printhead wipercomprising: projecting a reproducible quantity of servicing fluid froman applicator pump through atmosphere onto at least one of saidprinthead and said wiper; and wiping said printhead by moving said wiperwith respect to said printhead to remove unwanted accumulations fromsaid printhead.
 20. The method of claim 19, further comprisingmaintaining a source of servicing fluid in an uncontaminated state bypreventing contact of said applicator with said printhead and saidwiper.
 21. A system for servicing a portion of a printhead of an inkjetprinter having a printhead reciprocally moved by a carriage and a wiperpositioned and adapted to move with respect to the printhead in wipingcontact therewith to remove unwanted accumulations from a portion of theprinthead, comprising: a source of printhead servicing fluid; aservicing fluid applicator comprising a pump having an outlet forprojecting a reproducible quantity of servicing fluid through atmosphereonto at least one of said printhead and said wiper; and means fortransferring servicing fluid from said source of servicing fluid to saidservicing fluid applicator.
 22. The system of claim 21, wherein saidapplicator projects a metered amount of servicing fluid applied onto atleast one of said wiper and said printhead.
 23. The system of claim 22,wherein said pump is a low volume spray pump.
 24. The system of claim21, wherein said source of servicing fluid comprises a collapsiblereservoir.